Note: Descriptions are shown in the official language in which they were submitted.
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Description
Reclosable Storage Bag
Technical Field
This invention generally relates to packaging and
5 more speci~ically to a storage bag that is easily reclosed
and to methods and apparat;us for making such a storage
bag.
Background Art
Extensive efforts have been directed to producing a
storage bag that is easily opened and then reclosed.
These e~orts have led to criteria ~or judging the
potential success of such storage bags. Consumers require
that such bags must be easily opened, reclosed and then
reopened. The method o~ r.eclosure must be positive. From
15 a manu~acturer's standpoint, the method and apparatus used
to form the bag and reclosure structure must be easily
added to a production line, operate without any
appreciable reduction in production rates, add mi n; m~ 1
production costs, have the capacity to be used with bags
20 requiring a freshness seal and produce little or no waste
material.
United States Letters Patent No. 5,284,002 discloses
a reclosable storage bag and a method and apparatus for
manufacturing such bags that meets essentially all the
foregoing criteria. In accordance with that disclosure, a
storage bag with a reclosure tie is produced by forming a
sealable, elastic, polymeric film into an open-ended,
hollow cylinder that extends along a first axis. A
portion of the film cylinder is clamped along a second
30 axis that is transverse to the first axis to form a margin
portion in coextensive film wall portions. The margin has
~ first and second sections disposed along the second axis
to provide a boundary bet~Yeen successive storage bags. A
line of perforations is formed in the margin portion that
is parallel to the second axis. The film walls are also
severed in the margin por1ion along a severance line that
is parallel to and spaced from the second axis. The
perforation and severance line define a removable
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disclosure tie between the perforation and severance lines
and an adjacent first sealing area.
In accordance with that disclosure, impulse or A
resistance sealing jaws form first and second seals. The
5 first seal is formed in the film walls along a line in the
first sealing area that is parallel to the second axis and
is coextensive with both the first and second sections.
The second seal is parallel to the second axis and extends
only across the first section to produce a tail while the
10 film walls in the second section remain unsealed and form
a loop. The tie is looped around an opened bag with the
tail through the loop. Pulling the tail tightens the loop
thereby reclosing the bag.
In the foregoing patent, a resistance sealing jaw
15 includes a heat sealing bar having an extensive area
across the first portion to form the seals for the
reclosure tie. In some situations it has been found that
this resistance heating structure, that is proximate
knives that perforate and sever the film cylinder, can
20 heat the knives so film material touching the knives can
soften and accumulate on the knives. This accumulation
ultimately requires that the apparatus be stopped so the
knives cam be removed and cleaned. Such stoppages can
reduce the productivity of resistance sealing jaws by a
25 measurable and therefore oftentimes unacceptable amount.
Disclosure of Invention
Therefore it is an object of this invention to
provide a method and apparatus for manufacturing a
reclosable bag that is easy to open, that contains a
30 reclosure tie that facilitates the subsequent closure and
reopening of the bag and that enables maintenance of high
production rates normally associated with such apparatus.
Still another object of this invention is to provide
a reliable and economical method and apparatus for
35 manufacturing a reclosable bag.
Still another object of this invention is to provide
a structure for a reclosable storage bag that is readily
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adapted for manufacture Oll resistance sealing packaging
equipment.
Still another object of this invention is to provide
resistance sealing jaws for reliably and economically
5 manufacturing a reclosable storage bag.
In summary and in accordance with one aspect of this
invention, a storage bag with a reclosure tie is produced
by forming heat-sealable elastic polymeric film into an
open-ended, hollow structure formed by walls of the film
10 and extending along a fir,st axis. A portion of the hollow
structure is clamped along a second axis that is
transverse to the first axis to form a margin portion in
coextensive film wall porlions. The margin portion has
first and second sections disposed along the second axis
to provide a boundary between successive storage bags. A
line of perforations is formed in the margin portion that
is parallel to the second axis. The film walls are also
severed in the margin por~ion along a severance line that
is parallel to and spaced from the second axis. The
20 perforation and severance lines define a removable closure
tie between the perforation and severance lines and an
adjacent first sealing area. A first seal is formed in
the film walls along a line in the first sealing area that
is parallel to the second axis and coextensive with both
the first and second sections. A second seal that is
parallel to the second ax:is and extends only across the
first section comprises a plurality of sealed portions
that extend parallel to the second axis whereby portions
of the first section are sealed and unsealed.
In accordance with another aspect of this invention,
apparatus for manufacturing storage bags from a continuous
cylinder lying along a first axis and formed of a heat
sealable polymeric film includes a pair of counterfacing
sealing jaws. The sealing jaws include a plurality of
35 coacting gripper portions that engage and hold the film
walls therebetween. Heat:ing assemblies in each of the
sealing jaws include means for providing at least one seal
across the entirety of the storage bag. A second portion
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of the heating assembly includes a plurality of sealing
fingers in each of the jaws that coact to produce a series
of spaced seals in an area coextensive with the first
section parallel to the second axis. Cooling means are
interfitted around the sealing fingers to direct a gaseous
coolant across fixed perforation and severing knives.
Brief Description of Drawinqs
The appended claims particularly point out and
distinctly claim the subject matter of this invention.
10 The various objects, advantages and novel features of this
invention will be more fully apparent from a reading of
the following detailed description in conjunction with the
accompanying drawings in which like reference numerals
refer to like parts, and in which:
FIGS. 1 through 3 depict a reclosable storage bag
constructed in accordance with this invention;
FIG. 4 is a perspective view of one embodiment of
first and second sealing jaws for producing the reclosable
bag shown in FIGS. 1 through 3 in accordance with other
20 aspects of this invention;
FIG. 5 is a cross-section of the sealing jaws in a
partial cross-section while they are apart;
FIG. 6 is a cross-section of the sealing jaws when
they are moved together to form a seal between successive
25 bagsi
FIG. 7 is an exploded view of one sealing jaw shown
in FIG 4; and
FIG. 8 is a front view of the other sealing jaw shown
in FIG. 4.~0 Best Mode for Carrying Out the Invention
RECLOSABLE BAG 100
Fig. 1 of the drawings depicts a bag 100 that is
formed of an elastic coextruded polymer such as high
density polyethylene and ethyl vinyl acetate or a
copolymer including polyethylene. When heat is applied to
adjacent film layers, the material seals, typically by
fusing. These films are also characterized by reasonably
high resistance to puncture and to the initiation of a
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tear. It is intended that the phrase "sealable elastic
polymeric material" include all such polyethylene-based
. materials as well as other materials that exhibit similar
characteristics. Such malerials may also be co-extruded
5 with other films for part:icular applications and still use
the ~oregoing characteristics. FIG. 1 also depicts an
adjacent, or lower, bag 101 after being severed from the
bag 100 as occurs in a no~mal production of successive
storage bags. Each bag has the same basic construction.
Using the storage bag 100 as an example, the film
forms a generally cylindrical open-ended pouch 102
comprising a sheet of the sealable elastic polymeric
material or film form wrapped around a cylinder or
mandrel. The edges overlap and produce a longit~l~in~lly
15 extending backseam 103. A "bottom" seal 104 and a "top"
seal 105 close the ends of the pouch 102 so the bag can
store food or other articles. A perforation line 106
defines a boundary between the storage bag 100 and an
attached, integral reclosable tie 110.
Specifically the reclosable tie 110 constitutes a
margin portion and includes film layers on extensions 111
and 112 beyond the seal 105. The extensions 111 and 112
terminate at margin end portions 113 and 114 and the
reclosure tie 110 lies along an axis 115 that parallels
the top seal 105. Two sets 116 and 117 of aligned,
elongated, spaced fused seals parallel to the axis 115 and
extend from the margin end 113 to a position intermediate
the backseam 103 and the margin end 114. A top edge 118
of the extensions 111 and 112 constitutes a parting line
30 for adjacent bag.
The portion of the extensions 111 and 112 that are
- coextensive with the spaced seal sets 116 and 117 along
the axis 115 produce a tail portion 120 in which the
~ layers 111 and 112 are fused together at spaced locations.
35 The rem~;n;ng portions of the extensions 111 and 112
including the end 114 form a loop portion 121. As shown
in FIG. 1, therefore, each of a series of storage bags
such as storage bags 100 and 101 has an integral extension
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of the film forming two layers beyond a top seal line.
The extensions form a tail and loop structure that can be
readily torn from the bag along the perforation line 106.
To open the bag, a consumer tears the reclosable tie
110 from the bag 100 along the perforation 106 as shown in
FIG. 2. Then the consumer separates the film layers along
the top freshness seal 105 to open the bag fully. After
some of the contents are removed, the individual gathers
the bag 100 above the r~m~;ning contents to form a closed
10 neck 122 as shown in FIG. 3, wraps the reclosure tie 110
around the neck 122 and passes the tail portion 120
through the loop portion 121. When the consumer pulls the
tail portion 120, the reclosure tie 110 slides
longitll~;n~lly such that the loop 121 adjacent the margin
15 end 114 slides along and tightens the noose formed around
the gathered neck 122.
All pressure on loop 121 is applied against the end
114 that preferably is free of any material that might
otherwise delaminate, such as the backseam 103. When the
20 loop 121 is firmly cinched in place and the tail portion
120 is released, the material, that stretched in tension,
relaxes. The end margin 114 of the loop 121 cinches
against the tail portion 120 thereby preventing its
inadvertent loosening. However, as is characteristic in
such loops, intentional release of the reclosure tie 110
is readily accomplished by sliding the end of the loop 121
toward the margin end 113 of the tail portion 120 thereby
releasing the cinching action and enabling a consumer to
readily remove the closure tie.
The bag 100 achieves certain objects of this
invention. Primarily the reclosure tie 110 is formed
integrally with the bag during the bag forming and filling
processing and only with a nomin~l amount of additional
material. Thus, the cost of the bag 100 should not be
35 significantly greater than that of a conventional bag
without the reclosure tie 110. Moreover, conventional
form, fill and seal pouch apparatus can produce bags, such
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as the bag 100 o~ FIGS. 1 through 3, successively without
significant modification.
APPARATUS FOR FORMING BAGS
As known in the art, typical vertical ~orm and ~ill
5 apparatus passes a film oE the sealable elastic polymeric
material from a supply roLl past a guide roller and over a
panning shoulder to ~orm the film into a folded,
vertically moving web abo~t a cylindrical mandrel. First
sealing apparatus forms the backseam 103 as the web moves
10 over the mandrel to produce a continuously advancing open-
ended film cylinder. A hopper dispenses a measured amount
of contents through the mandrel into a pouch that has been
formed above a bottom seal by closed sealing jaws during a
prior operation.
Each of FIGS. 4 through 6 depicts a set 150 of
sealing jaws that mount ~or reciprocal motion to and from
a moving web 151 of film (i.e., horizontally in FIGS. 5
and 6). FIGS. 5 and 6 particularly depict the disposition
of the individual sealing jaws 150L and 150R on opposite
sides of the moving web 151. In the art, individual jaws
in a set 150 are sometimes referred to as "front" and
"rear" sealing jaws. For purposes of this discussion, it
is assumed that the front jaw 150L is on the left and that
the rear jaw 150R is on the right. When individual
25 elements in the sealing jaws have complementary functions,
their locations are designated by the suffix "L~ if
located on the front or left sealing jaw and "R" if
located on the rear or xight sealing jaw. In collective
reference to such elements, the reference numeral will be
30 used without a suffix. For example, the sealing jaws 150L
and 150R are referred to collectively as sealing jaws 150.
In use, the sealing jaws 150 maybe transported on a
carriage to an upper position in the retracted position
~ shown in FIG. 5. Mechallisms on the carriage then move the
sealing jaws 150L and 150R toward each other to capture
the web material 151 between them. Such carriages and
reciprocating mechanisms are well known in the art. Then
such a carriage moves downwardly to move the web material
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151 along a vertical axis over the mandrel to pull the
material to a lower position. After the sealing jaws 150L
engage the web material 151, knives perforate and cut the
web material 151 along lines 106 and 118. Then the
sealing jaws 150 ~orm the upper seal 105 in the bag 101
and the lower seal 104 in the next bag 100 and the spaced
seal sets 116 and 117. The apparatus simultaneously
dispenses contents from the hopper through the mandrel to
fill the bag 100.
When the sealing jaws 150 reach the bottom of travel
along the mandrel axis, the sealing jaws 150 retract. At
this point the bottom bag 101 drops away with its
contents. The carriage then moves sealing jaws 150 back
along the mandrel axis to a position corresponding to the
15 top of the filled bag. At the top of this motion, the
sealing jaws 150 are positioned to close, grab the web
material 151 above the contents and pull another section
of film into appropriate position to form another bag.
Referring to FIGS. 4 and 5, the sealing jaws 150L and
150R include outer frames 152L and 152R with upper gripper
bars 153L and 153R with oppositely facing web gripping
surfaces 154L and 154R. Lower gripper bars 155L and 155R
define oppositely facing web gripping surfaces 156L and
156R. When the sealing jaws 150L move from their
25 retracted positions shown in FIG. 5 to the closed
positions shown in FIG. 6, the gripping surfaces 154 and
156 engage or clamp the web material 151 between the
sealing jaws 150. As previously described, that portion
of the web material 151 between the upper and lower
30 gripping bars 153 and 155 constitutes a margin portion
between the bottom of an upper bag and the top of a lower
bag such as the margins formed by the extensions 111 and
112 in FIG. 1.
Still referring to FIGS. 4 through 6, after the
sealing jaws 150L move to the closed position shown in
FIG. 6, additional operations occur. First, a cutting
knife 157 on the movable sealing jaw 150L advances through
the web material 151 into a recess 158 in the sealing jaw
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_g_
150R along the parting line 118 shown in FIG. 1. A
per~oration knife 160 also moves through the web material
151 into a recess 161 in the ~ixed sealing jaw 150R to
form the perforation line 106 shown in FIG. 1. This
5 operation preferably occurs after upper internal grippers
162L and 162R and lower internal grippers 163L and 163R
engage to stabilize the web material 151 during the
cutting and sealing operations. However, in some
situations upper and lowe:r internal gripper bars 162 and
163 could engage essentially simultaneously with contact
between the knives 157 and 160 engage the web material
151.
Thereafter, counterfacing elonyated sealing surfaces
in sealing elements 164L .and 164R produce the seals 104
and 105 and the spaced seal sets 116 and 117.
Specifically sealing surfaces 104L and 104R form the seal
104; sealing surfaces 105L and 105F, seal 105; spaced
sealing surfaces 116L and 116R, the set o~ seals 116; and
spaced sealing surfaces 117L and 117F, the set of seals
20 117.
SEALING JAW STRUCTURE
With this basic understanding of the construction and
operation of the sealing jaws 150, the detailed structure
o~ the left sealing jaw 150L and right sealing jaw 150R
25 can be better appreciated, particularly with respect to
the objectives of this in.vention. Each of the sealing
jaws 150L and 150R comprises respectively, the outer
frames 152, cutting and perforating structures including
the knives 157 and 160, the inner grippers 162 and 163,
30 the heating blocks 164 and cooling elements 165. Th
outer frame 152R comprises the generally horizontally
disposed upper and lower outer gripper bars 153R and 155R
and a vertical backplate 170R that extends the ~ull width
~ - of the sealing jaw 150R . Consec~uently, the outer ~rame
35 152R has a rigid U-shaped structure. Typically the frame
152R is ~ixed to the previously discussed carriage
structure for reciprocal motion. The outer frame 152L
includes the upper and lower outer gripper members 153L
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--10--
and 155L and a vertical backplate 170L that define a rigid
U-shaped structure. The outer frame 152 can be formed of
discrete portions or as a single integral member. The
outer frames 152 generally mount on the carriage along
rails or other structures for allowing the outer frames
152 to reciprocate in a horizontal plane with respect to
the web material 151. An actuator 171 and link 172 shown
in FIG. 4 schematically depict the apparatus for producing
this simultaneous reciprocal motion of both sealing jaws
150L and 150R.
FIGS. 4 through 7 also depict resilient rectangular
gripping pads 173 and 174 that are disposed in the end
surfaces 154L and 156h of the upper and lower gripping
bars 153L and 155L. The pads 173 and 174 can also be
formed with other cross-sections to fit in complementary
milled slots to optimize the particular interface between
the resilient pads 173 and 174 and the counterfacing
surfaces 154R and 156R. In some applications it may also
be desirable to incorporate resilient pads in the gripping
surfaces 154R and 156R. The gripping surfaces 154R and
156R may also be rough~n~fl or corrugated to improve the
gripping force exerted against the web 151 when the
sealing jaws 150 close to the position shown in FIG. 6.
Now referring to the heating blocks 164, the heating
block 164L mounts for linear motion in a horizontal
direction between the positions shown in FIGS. 5 and 6.
The heating block 164R attaches to the backplate 170R by
means of shock resistent mounts 175 to relieve any
stresses that occur when the heating block 164L moves into
contact with the stationary heating block 164R. Apparatus
for reciprocating the heating block 164Lis known and
represented diagrammatically by an actuator 176 and
linkage 177.
Both the heating blocks 164L and 164R otherwise have
identical structures so reference is made particularly
only to the heating block 164R for an initial
understanding of construction and function of the heating
blocks. Specifically the heating block 164R includes a
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--11--
base 180R that carries a heating apparatus represented
schematically as heating cartridges 181R. Upper and lower
horizontal arms 182R and 183R extend parallel and
proximate to the upper and lower gripper bars 153R and
5 155R respectively. The free ends of the arms 182R and
183R are chamfered to produce the heat sealing surfaces
104R and 105R. Typically these heat sealing surfaces are
coated with a material such as polytetrafluoroethylene for
facilitating the release of the heat sealing jaws from the
10 web material 151. As particularly shown in FIG. 6, this
structure produces the heat sealing surfaces 104L and 105L
that counterface sealing surfaces 104R and 105R on the
heat sealing block 164R that, collecti~rely, produce the
corresponding seals 104 and 105 in the bag as shown in
15FIG. 1.
Also particularly shown in reference to FIGS. 5, 6
and 8, the heating block 164R contains a plurality of
individual fingers that form the heat sealing surfaces
116R and 117R. In this particular case the structure of
20 these can be best seen by referring to FIGS. 4 and 7 that
depict the front jaw 150L. The structure includes a first
plurality of fingers l90L extending along a line parallel
to the axis 115 and proximate the upper internal gripper
bar 162L. Each of the fingers l90Lis an integral portion
25 of the base 180L and has chamfered edges l91L to form the
vertical sealing surfaces 117L.A similar set of fingers
192L are spaced along a line parallel to the axis 115 and
proximate the lower internal gripper bar 163L. Each
finger 192L contains chamfered surfaces 193L to form the
30 vertical heat sealing surfaces 116L. The heat sealing
surfaces 116L and 117L thereby form a series of spaced
elongated sealing surfaces disposed at opposite sides of
the axis 115 and intermediate the internal grippers 162L
and 163L. Each of the fingers l90L and 192L faces a
35 corresponding finger 190 for 192R.
The fingers l90R and 192R are not chamfered thereby
to provide planar sealing surfaces 116R and 117R for
aligning with the counterfacing chamfered fingers that
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define sealing surfaces 116L and 117L. Aswill be
apparent, when the actuator 171 and the actuator 176
advances the sealing jaw 150L and the heating block 164L
to the positions shown in FIG. 6, the heat sealing
surfaces 116L and 116R and 117L and 117R produce the rows
of spaced seals 116 and 117, respectively.
In accordance with one aspect of this invention, each
of the sealing jaws 150 includes cooling elements 165L and
165R having substantially the same construction.
Initially reference is only made to the cooling element
165L as shown in FIG. 7. This element 165L comprises a
rectangular block of heat conductive material having a
central passage 194L formed therethrough for receiving a
coolant, such as cooled air or other gaseous coolant, and
15 discharging it from the other end. In this particular
embodiment the passage 194Lis shown as a through passage,
but the passage might include angular offsets to
accommodate the configuration of a particular set of jaws.
The cooling element 165L additionally comprises a
20 series of upper notches 195L that correspond in position
to the location of the fingers l90L and a corresponding
set of lower notches 196L that register with the fingers
192L. Upper fingers 197L and lower fingers 198L extend
intermediate the fingers l90L and 192L, respectively.
25 Thus the cooling block 165L essentially interfits in a
ch~nnel200L defined between the fingers l90L and 192L and
partially surrounds each sealing finger.
The cooling block 165L additionally comprises a
plurality of upper air passages 201L and lower air
30 passages 202L that exit through top and bottom surfaces of
the block 165L including through the fingers 196L and
197L. These passages may extend vertically from the
passage 193L or may be angled to direct air in a direction
from the base 180L toward the web 151. As the surfaces of
35 the upper fingers 196L and the lower fingers 197L are
proximate the cutting knife 157 and the perforation knife
160, the ejected cooling air is directed along the surface
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-13-
of the knives to maintain them at a relatively cool
temperature.
With respect to the :rear sealing jaw 150F, the
cooling block 165R has a corresponding structure, except
that the upper and lower gripper bars 162R and 163R are
formed integrally with the cooling block and define the
recesses 158 and 161 through which air also is ejected
toward the web 151. Conse~uently, the cooling air flowing.
over the blades 157 and 160 from the cooling block 165L
10 tends to maintain the knife blades at a temperature that
is below the fusion temperature for the polyethylene ~ilm
of the web 151. After the knives penetrate, the combined
air flow from both sealing jaws 150 further act to
maintain the kni~es below the melting temperature o~ the
polyethylene. This essentially overcomes any tendency of
film to accumulate on the knife blades and allows them to
form cleaner cuts and perforations and to penetrate and
retract from the film without dragging melted film on
their respective surfaces.
The fixed upper and lower inter:nal grippers 162R and
163R and the movable upper and lower grippers 162L and
163L support the web material 151. Each of the movable
grippers 162L and 163Lis formed as a plate that lies
parallel to the axis 115 and that is mounted for
reciprocal motion with respect to the outer frame 152L and
heat sealing block 164L. Upper springs 210 and lower
springs 211 attach to the backplate 170L and extend
through apertures in the heating block base 180L to drive
the upper and lower movable internal grippers 162L and
163L toward the web material 151 to a position shown in
FIG. 5 wherein the free ends 212L and 213L extend beyond
- the leading cutting edges of the knife blades 157 and 160.
These ends 212 are corrugated or formed to have an erose
edge surface that engage complementary surfaces 212R and
213R at the ends of fixed internal gripper bars 162R and
163R. Whereas the coolin.g block 165L shown in FIG. 7is
shown with an interrupted. surface at each of the passages
194L and 195L, the upper and lower portions 214 and 215 of
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the cooling bars are continuous on the structure, thereby
to provide a continuous backing surface for the film.
Springs 210 and 211 are adjustable through some adjustment
structure, as represented by adjusting screws 215 shown in
5 FIGS. 5 and 6.
OPERATION
As the actuator 171 in FIG. 4 drives its linkage 172
and the connected sealing jaws from the retracted position
shown in FIG. 5 toward the closed position shown in FIG.
10 1, contact initially occurs between the internal grippers
162 and 163. As the sealing jaws 150 close further, the
internal grippers 162L and 163L compress the springs 210
and 211. Consequently, the internal grippers 162 and 163
hold the web material 151 in a plane while portions 213R
15 and 214R of the cooling block 165R intermediate the
fingers 190R and 192R and the recesses 158 and 161,
respectively, back the web 151.
As actuator 171 in FIG. 4 displaces the sealing jaws
still closer together, the gripper pads 173 and 174
20 eventually clamp the web material 151 against the surfaces
154R and 156R. At this point, the various grippers 153,
155, 162 and 163 fully support the web material 151 in a
planar configuration necessary to assure seals that are
functionally and aesthetically acceptable. Additional
25 displacement of the heating block 164L to the right by the
actuator 176, clamps the film web material between the
sealing surfaces 104, 105, 116 and 117 to form the
corresponding seals. Although the sealing sur~aces are
above the fusing temperature, the cooling air bathing the
30 blades 157 and 160 prevents fusing at those locations
while the seals 104, 105, 116 and 117 form.
After a dwell interval during which the polyethylene
seals form, the actuator 176 in FIG. 4 withdraws the
movable heat sealing body 164L toward the backplate 170L
35 until the heat sealing surfaces 104L, 105L, 116 and 117L
and knives 157 and 160 move behind the plane defined by
the gripping surfaces 154L and 156L, such as shown in FIG.
5. This occurs while the external grippers 153 and 155
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and internal grippers 162 and 163 continue to support the
web material 151. As the blades 157 and 160 continue to
be cooled by the cooling air, they tend to withdraw from
the film without dragging polyethylene material with the
5 blades thereby to prevent the film build up and to leave a
cut edge 118 ~ormed by the blade 157 and the perforated
line 106 formed by the kn:ife 160 in an aesthetically
pleasing form without rough edges or dross.
Next, the actuator 171 in FIG. 4 begins to retract
the sealing jaws 150 from each other. Initially the
gripping surfaces 154L and 156L disengage from the web
material 151, but the internal grippers 162 and 163
continue to support the web material 151 proximate the
blades 157 and 160. . Further retraction or separation
of the sealing jaws 150 enables the internal grippers 162L
and 163L to disengage from the web material 151, so the
bag formed below the knife blade 157 drops as a finished
product. The seal 104 formed by the sealing surfaces 104L
and 104R ;mm~;ately above the grippers 162L and 162R
20 defines the bottom seal across the next bag to be filled
= and sealed in succession. As previously indicated, after
the sealing jaws 150 are Eully retracted, their supporting
carriage elevates or otherwise positions the sealing jaws
150 for Eorming the next jeal whereupon the process
25 repeats.
In summary there has been disclosed an embodiment of
a reclosable storage bag that allows an individual to
reclose a sealed bag after it is opened and one embodiment
of sealing jaws that produce that bag and that operate
30 more efficiently than prior art devices. Like prior art
reclosable bags the assignee of this invention, the bag is
- easy to open and contains a reclosure tie that facilitates
subsequent closure and reopening of the bag. The bag,
with its integral reclosure tie, does not require the
35 addition of any discrete elements or special components to
the bag. Manufacturing does not produce waste materials
and any additional manufacturing costs are limited
primarily to the cost of additional material and a small
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-16-
margin portion. In each bag the reclosure bag is readily
detached and used and, with its strong internal loop
portion and tail portion, provides an easy to use
reclosure structure.
The sealing jaws that produce the spaced sets of
seals along parallel axes across a portion of this
reclosure tie have a structure that m;n;m; zes the
accumulation of film on components of the sealing jaws
during manufacture. Reduciny the accumulation rate
10 extends the interval during which the system can operate
without the requirement for cleaning or other preventive
maintenance. Increasing the operating time as a
percentage of total available operating time has the
effect of increasing throughput and further reducing the
cost of the reclosure tie. Moreover, the inner and outer
gripper bars fully support the web material during the
cutting, perforation and sealing operations to further
assure a reliable formation of the necessary seal of the
various seals and the effective operation of the knives.
20 This assures the quality of the overall bag with respect
to the integrity of any freshness seals and the aesthetic
appearance of the sealed margin portion including the
reclosable tie. Moreover, the sealing jaws constructed in
accordance with this invention limit all the moving parts
25 of the structure to a single jaw. The other sealing jaw,
with the exception of some stress relief mounts, contains
fixed components. This further increases the reliability
of the overall manufacturing apparatus.
This invention has been disclosed in terms of certain
30 embodiments. It will be apparent that many modifications
can be made to the disclosed apparatus without departing
from this invention. The specific configuration of the
heat sealing fingers could be modified to produce
different seal configurations. If bags do not have bag
seams, the extension of the sets of spaced seals can be
varied for optimizing different relationships between the
length of the loop and the tail portion. The sealing jaws
may or may not include the heat sealing surfaces for
CA 0222~i4~il 1997-12-22
WO 97100767 PCT/US96~10671
producing freshness seals at both openings. Alternative
methods, operating secluences and apparatus may also be
substituted ~or the speci~ically disclosed methods and
apparatus with the attA;n~nt or some or all o~ the
speci~ic advantages of the disclosed embodiments. For
example, the particularly disclosed sealing jaws move
vertically on a carriage to draw the web material o~f a
mandrel. This invention is also adapted for systems in
which other apparatus draws the web material past the
sealing jaws so that vertical travel of the sealing jaws
is not necessary. Therefore, it is the intent of the
appended claims to cover all such variations and
modi~ications as come within the true spirit and scope of
this invention.
